Kushner's attorney has said his client will fully cooperate. "As Mr. Kushner has been saying since March, he has been and is prepared to voluntarily cooperate and provide whatever information he has on the investigations to Congress," the lawyer, Abbe Lowell, said in a statement.

Kushner will not be under oath during his appearance Monday, and the session will not be in public.

Democrats have pointed out that those circumstances could easily allow the president’s son-in-law and senior adviser to avoid directly answering questions about his alleged links to Russia.

Ahead of the meeting, Trump Jr. had been promised damaging information about Hillary Clinton, according to emails he released earlier this month — although the president's son has said the meeting did not produce any information and that Veselnitskaya wanted to discuss an adoption program of Russian children.

Democrats have pounced on the meeting as evidence that Trump Jr. was willing to collude with a foreigner purporting to have information tied to the Russian government to help his father's presidential campaign and influence the results of the election.

The Senate Intelligence Committee is investigating Russia's alleged interference in the 2016 presidential contest. U.S. intelligence agencies have concluded that Moscow's covert operation was intended to damage Clinton's campaign and evolved into an attempt to help Trump win.

Kushner, on Monday, also may face questions over whether he tried to set up a secret back channel way of communicating with the Russians.

President Donald Trump delivers remarks at the beginning of a meeting with his son-in-law and senior advisor Jared Kushner and government cyber security experts at the White House on Jan. 31, 2017.Chip Somodevilla / Getty Images

The Washington Post reported in May that Kushner had, in December 2016, allegedly proposed to the Russians setting up a secret communications channel using secure diplomatic facilities. NBC News has not confirmed that report.

Congressional sources told NBC News days later that members of the Senate and House Russia probes were looking into whether Kushner had attempted to create the channel so he could find somebody in Moscow to buy a the massively expensive 41-story tower at 666 Fifth Avenue from his family's real estate company.

Kushner Companies bought the building in January 2007 for $1.8 billion and have been losing cash on it ever since.